java - Performing rawQuery and place resulting value for each row in database -

so on add database, perform select statement result , add separate column in database, , looks follows:

public void addgaslog(gaslog gaslog){         // reference writable db         sqlitedatabase db = this.getwritabledatabase();          // create contentvalues add key "column"/value         contentvalues values = new contentvalues();         //...          cursor cursor = getwritabledatabase().rawquery("select (" + gaslog.getodometer() + " - y.odometer) / " + gaslog.getgallons() + " mpg gaslog x, gaslog y y.odometer = (select max(z.odometer) gaslog z z.odometer < " + gaslog.getodometer() + ")", null);         try {               if (cursor.movetofirst()) {                    mpg = cursor.getstring(0);               }             } {               cursor.close();             }         values.put(key_mpg, mpg);          log.d("mysqlitehelper", key_mpg);          // insert         long gaslog_id = db.insert(table_gaslog, //table                 null, //nullcolumnhack                 values); // key/value -> keys = column names/ values =           db.close(); } 

so good, performs calculation needed in select statement , inserts correct value in mpg column row.

what need able use similar functionality, , perform on each row in database... run select statement on each row, , pass value mpg column each row hits.

i know few values change, gaslog.getodometer() need instead value of "odometer" column row , gaslog.getgallons() need value "gallons" column row.

any appreciated.

edit: looking put results question new method can run separately, go through each row on database , update them all.

edit2:

this method created creating blank columns

public void updatempg(){         sqlitedatabase db = this.getwritabledatabase();         cursor cursor = getwritabledatabase().rawquery("select ('odometer' - y.odometer) / 'gallons' mpg gaslog x, gaslog y y.odometer = (select max(z.odometer) gaslog z z.odometer < 'odometer')", null);         contentvalues values = new contentvalues();         try {             cursor.movetofirst();             while (true) {                 mpg = cursor.getstring(0);                 values.put(key_mpg, mpg);                 long gaslog_id = db.insert(table_gaslog, null, values);                 if (cursor.islast())                     break;                 cursor.movetonext();             }         } {             cursor.close();         }         db.close();      } 

edit3:

here how go through rows in database , modify mpg column value in table_gaslog table.

cursor cursor = getwritabledatabase().rawquery("select (" + gaslog.getodometer() + " - y.odometer) / " + gaslog.getgallons() + " mpg gaslog x, gaslog y y.odometer = (select max(z.odometer) gaslog z z.odometer < " + gaslog.getodometer() + ")", null); try {     cursor.movetofirst();     int key = 1;     while (true) {         mpg = cursor.getstring(0);         values.put(key_mpg, mpg);         db.update(table_gaslog, values, "_id=?", new string[]{string.valueof(key)});         if (cursor.islast())             break;         cursor.movetonext();         key++;     } } {     cursor.close(); } db.close(); 

this code iterate on entire result set , extract mpg value in each row , insert table_gaslog database.

edit: add more rows table_gaslog. comment, understand need update row. in case, instead of db.insert() method, please use:

update(string table, contentvalues values, string whereclause, string[] whereargs) 

your clause depend on whatever condition is.